Via Michael Cader's Publisher's Lunch, he notes the cover article in Costco's in-house magazine on the stores' book buyers and the corresponding importance Costco represents to today's publishers. Len Riggio railed on the discounts offered to big box retailers generally suggesting that they were unearned (relative to B&N's importance) but it would be difficult to argue that when in some cases Costco is buying up 20-25% of the first print run. Jeff Rogart, VP Sales at Harpercollins is quoted as saying Costco is frequently their number one or two retailer on certain selected titles.
Selection of titles is matched to the slightly upscale demographic of the Costco customer (clearly the reason I never saw this publication) and indeed like any good retailer they closely monitor which titles their customers gravitate to and believe they can spot buying trends much earlier than other book retailers. Also noted in the article, the buyers have had similar success with magazines.
Read the whole thing.